Hey MilwaukeeVolvo,

I don't have firsthand experience with any power mods on the 855, but I live in the same city so I thought I'd post. :) I think you'll run into the same aftermarket situation I did with my souped-up non-turbo Mazda (heh) -- since there was a turbo version of the same car, there's just not much call from enthusiasts for NA motor mods. I've seen advertised probably the same products you have -- ECU modification, from $400-700; intake mod and catback exhaust. Gains from any or all probably won't be all that significant, at least compared to the world of boost.

Overall I'm pretty pleased with the 2.4L. It sounds cool, even in stock trim, and has competitive power output for its size. I wonder if the lack of aftermarket headers is explained by the stock unit being fairly well designed. Some issues that I find a bit disappointing about this powerplant are that it lacks the enhancements other brands bring to the NA table, like variable valve timing and variable intake runner length. In fact, I was surprised to see that volvo.com lists exactly the same power output for the NA motor in 2003 models. I guess Volvo answers enthusiasts' calls with this: "Do ya want the low-pressure or high-pressure turbo?"

Steve -- I wouldn't want my Volvo to sound like my rotary Mazda either ;)